JP2021004425A - Surface sizing agent for paper making, method for producing surface sizing agent for paper making and coated paper - Google Patents

Abstract

To provide a surface sizing agent for paper making that has excellent mechanical stability, causes little foaming, and exhibits excellent sizing effect, a method for producing a surface sizing agent for paper making, and coated paper.SOLUTION: A surface sizing agent for paper making has an emulsion particle that has a shell part and a core part, wherein the shell part has a surfactant (A) with a weight average molecular weight of 1,000-500,000, and the core part has a polymer (B) of a monomer component containing a styrene (b1), and an alkyl ketene dimer (C).SELECTED DRAWING: None

Description

The present invention relates to a surface sizing agent for papermaking, a method for producing a surface sizing agent for papermaking, and coated paper.

Generally, surface sizing agents for papermaking can be roughly classified into aqueous solution type and emulsion type, but the latter has a relatively low viscosity even if the solid content (nonvolatile content) is set high, has excellent handleability, and is a coating liquid. Has the advantage of being relatively small in foamability.

However, since the surface sizing agent for papermaking is unstable with respect to the mechanical share, when the paper is coated by a coating method such as a size press method in which a strong shearing force is applied, the emulsion is destroyed and the residue and foaming are generated. There is a problem that the operability is lowered due to the occurrence or uneven coating, and as a result, the size effect is lowered. In particular, this problem becomes remarkable when hard water such as industrial water in which metal ions are dissolved is used.

As a method for improving mechanical stability, for example, a means using a high molecular weight compound as a protective colloid together with an anionic or nonionic emulsifier can be considered, and in the presence of a styrene-maleic acid-based copolymer salt having a specific molecular weight. , A surface sizing agent containing an emulsion obtained by emulsion polymerization of hydrophobic unsaturated monomers such as styrenes has been proposed (Patent Document 1). However, the surface sizing agent was still inadequate in size effect and mechanical stability.

Japanese Unexamined Patent Publication No. 08-246391

An object of the present invention is to provide a surface sizing agent for papermaking, which has excellent mechanical stability, less foaming, and more excellent sizing effect; a method for producing a surface sizing agent for papermaking, and coated paper.

The present inventors examined various conditions by using an alkyl ketene dimer focusing on the point of enhancing the size effect and assuming that the mechanical stability deteriorates due to the use of the alkyl ketene dimer. We have found that a surface sizing agent for papermaking, which has an activator in the shell portion and a polymer of a specific monomer component in the core portion together with an alkyl ketene dimer, solves the above-mentioned problems, and has completed the present invention. That is, the present invention relates to the following surface sizing agents for papermaking, methods for producing surface sizing agents for papermaking, and coated paper.

1. 1. A shell portion containing a surfactant (A) having a weight average molecular weight of 1,000 to 500,000, and a core portion containing a polymer (B) of a monomer component containing styrenes (b1) and an alkyl ketene dimer (C). Surface sizing agent for papermaking containing emulsion particles having.

2. 2. The surface sizing agent for papermaking according to item 1 above, wherein the amount of the component (A) used is 20 to 200 parts by weight with respect to 100 parts by weight of the total of the components (B) and (C) in terms of solid content weight.

3. 3. The above item 1 or 2, wherein the component (A) contains a polymer of a monomer component containing at least one selected from the group consisting of styrenes (a1) and α-olefin (a2), and / or starches. Surface sizing agent for papermaking.

4. The surface sizing agent for papermaking according to any one of items 1 to 3 above, wherein the monomer component (B) further contains (meth) acrylic acid ester (b2).

5. The surface sizing agent for papermaking according to any one of the above items 1 to 4, wherein the monomer component (B) further contains an unsaturated monomer (b3) having a hydrophilic group.

6. The surface sizing agent for papermaking according to any one of the above items 1 to 5, wherein the component (C) is represented by the general formula (1).
(In the formula, R ¹ and R ² represent alkyl groups or alkenyl groups having 12 to 24 carbon atoms, respectively, and may be the same or different.)

7. Any of the above items 1 to 6, wherein the ratio of the component (B) and the component (C) used is (B) / (C) = 30/70 to 99/1 in terms of solid content weight. The described surface sizing agent for papermaking.

8. The surface sizing agent for papermaking according to any one of the above items 1 to 7, wherein the volume average particle diameter of the emulsion particles is 50 to 300 nm.

9. The method for producing a surface sizing agent for papermaking according to any one of the above items 1 to 8, wherein the monomer component forming the component (B) and the component (C) are added dropwise to the component (A) to carry out emulsion polymerization. ..

10. A coated paper containing the surface sizing agent for papermaking according to any one of the above items 1 to 8.

According to the surface sizing agent for papermaking of the present invention, it is excellent in mechanical stability, has less foaming, and exhibits an excellent sizing effect when it is made into paper.

The surface sizing agent for papermaking (hereinafter, also simply referred to as “sizing agent”) of the present invention is a shell containing a surfactant (A) having a weight average molecular weight of 1,000 to 500,000 (hereinafter, referred to as component (A)). Polymer (B) (hereinafter referred to as (B) component) and alkyl keten dimer (C) (hereinafter referred to as (C) component) of a monomer component containing a portion and styrenes (b1) (hereinafter referred to as (b1) component). Includes emulsion particles having a core portion containing). Hereinafter, each component will be described in detail.

The component (A) is one component that forms the shell portion of the sizing agent, and by functioning as a protective colloid, it has excellent mechanical stability and also has an effect of reducing foaming.

The component (A) usually has a weight average molecular weight (polyethylene oxide conversion value by gel permeation chromatograph method) (the same applies hereinafter) of 1,000 to 500,000. If the weight average molecular weight is less than 1,000, the emulsifying property of the components (B) and (C) tends to deteriorate, and if it exceeds 500,000, the viscosity of the surface sizing agent for papermaking becomes high, and the coating material is applied to the base paper. Workability tends to deteriorate. From the same point of view, it is preferably 5,000 to 100,000, more preferably 10,000 to 50,000.

The type of the component (A) is not particularly limited, but in the present invention, for example, styrenes (a1) (hereinafter referred to as (a1) component) and α-olefin (a2) (hereinafter referred to as (a2) component). A polymer of a monomer component containing at least one selected from the group consisting of () and / or starches are preferably used from the viewpoint of emulsifying property with the component (B) and the component (C).

The component (a1) is not particularly limited, and examples thereof include styrene, α-methylstyrene, tert-butylstyrene, dimethylstyrene, acetoxystyrene, hydroxystyrene, vinyltoluene, and chlorovinyltoluene. These may be used alone or in combination of two or more.

The amount of the component (a1) used is not particularly limited, but from the viewpoint of the size effect of the coated paper, the total of all the monomer components forming the component (A) is 100% by weight, and usually about 15 to 90% by weight. It is preferably about 30 to 80% by weight.

The component (a2) is not particularly limited, but for example, diisobutylene (2,4,4-trimethyl-1-pentene, 2,4,4-trimethyl-2-pentene, 2,4,4-trimethyl-1). -A mixture of pentene and 2,4,4-trimethyl-2-pentene), branched α-olefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene; 1 -Linear α-olefins such as hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 1-tetracocene, 1-triacontene; Examples thereof include cyclic α-olefins such as methylcyclohexene, vinylcyclohexane, 4-vinylcyclohexene, cyclopentene, and methylcyclopentene. These may be used alone or in combination of two or more. Of these, branched α-olefins are preferable, and diisobutylene is more preferable, from the viewpoint of the size effect of the coated paper.

The amount of the component (a2) used is not particularly limited, but from the viewpoint of the size effect of the coated paper, the total of all the monomer components forming the component (A) is 100% by weight, and usually about 5 to 60% by weight. It is preferably about 10 to 50% by weight.

In addition, either one or both of the component (a1) and the component (a2) may be used.

The monomer component forming the component (A) includes an unsaturated monomer (a3) having a carboxyl group (hereinafter referred to as a component (a3)), (hereinafter referred to as a component (a3)), from the viewpoint of emulsifying property with the component (B) and the component (C). It is preferable to use a combination of a meta) acrylic acid dialkylaminoalkyl ester (a4) (hereinafter referred to as (a4) component) and N, N-dialkylaminoalkyl (meth) acrylamide (a5) (hereinafter, (a5) component).

The component (a3) is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, or acid anhydrides, neutralized salts, half esters, and half esters thereof. Be done. These may be used alone or in combination of two or more. Of these, acrylic acid, maleic acid, and maleic anhydride are preferable from the viewpoint of polymerizability with the component (a1) and the component (a2).

The amount of the component (a3) used is not particularly limited, but from the viewpoint of emulsifying property with the component (B) and the component (C), the total of all the monomer components forming the component (A) is usually 100% by weight. It is about 5 to 80% by weight, preferably about 10 to 50% by weight.

The component (a4) is not particularly limited, and is, for example, (meth) acrylic acid-N, N-dimethylaminoethyl, (meth) acrylic acid-N, N-diethylaminoethyl, (meth) acrylic acid-N, N. -Dimethylaminopropyl, (meth) acrylate-N, N-dimethylaminobutyl, (meth) acrylate-N, N-dipropylaminoethyl, (meth) acrylate-N, N-dibutylaminoethyl and the like. Be done. These may be used alone or in combination of two or more.

The amount of the component (a4) used is not particularly limited, but from the viewpoint of emulsification with the component (B) and the component (C), the total of all the monomer components forming the component (A) is usually 100% by weight. Is 40% by weight or less, preferably 30% by weight or less.

The component (a5) is not particularly limited, and is, for example, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N. , N-Dimethylaminobutyl (meth) acrylamide, N, N-dipropylaminoethyl (meth) acrylamide, N, N-dibutylaminoethyl (meth) acrylamide and the like. These may be used alone or in combination of two or more.

The amount of the component (a5) used is not particularly limited, but from the viewpoint of emulsification with the component (B) and the component (C), the total of all the monomer components constituting the component (A) is usually 100% by weight. Is 20% by weight or less, preferably 10% by weight or less.

When the components (a4) and (a5) are used, it is better to quaternize a part or all of the amino groups derived from the components (a4) and (a5) to the components (B) and (C). It is preferable from the viewpoint of emulsifying property with the component. The degree of quaternization is not particularly limited, but is preferably at least about 10 mol% of the amino groups of the component (a4) and / or the component (a5) present in the obtained polymer, and is about 50 to 100 mol%. Is more preferable. As the quaternizing agent used for quaternization, various known agents can be used, and examples thereof include benzyl chloride, methyl chloride, dimethyl sulfate, glycidol, ethylene chlorohydrin, allyl chloride, styrene oxide, propylene oxide, epichlorohydrin and the like. Can be mentioned. The quaternization is usually carried out at a temperature of about 50 to 90 ° C. and a time of about 1 to 4 hours, and is usually carried out after the preparation of the polymer, but may be carried out before or during the polymerization.

Further, as the monomer component, an unsaturated monomer (a6) other than the components (a1) to (a5) (hereinafter, referred to as the component (a6)) may be appropriately used in combination. The component (a6) is not particularly limited, and examples thereof include (meth) acrylic acid ester, unsaturated monomer having a sulfonyl group; and (meth) acrylamide.

The (meth) acrylic acid ester is not particularly limited, and for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth). ) Isobutyl acrylate, -tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and the like.

The unsaturated monomer having a sulfonyl group is not particularly limited, and examples thereof include vinyl sulfonic acid, sodium styrene sulfonic acid, and sodium (meth) allyl sulfonate.

Examples of (meth) acrylamide include acrylamide and methacrylamide.

These (a6) components may be used alone or in combination of two or more. The amount of the component (a6) used is not particularly limited, but is preferably 10% by weight or less, with the total of all the monomer components forming the component (A) being 100% by weight.

The component (A) of the present invention can be obtained by appropriately combining the above-mentioned monomer components and polymerizing in the presence of a polymerization initiator. The polymerization method is not particularly limited, and a known method can be adopted. When solution polymerization is adopted, aromatic hydrocarbons such as benzene and toluene; ketones such as acetone and methyl ethyl ketone; alcohols such as n-propyl alcohol and isopropyl alcohol can be used as the solvent.

The polymerization initiator is not particularly limited, and for example, azo compounds such as 2,2'-azobisisobutyronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile; and benzoyl peroxide, Organic peroxides such as cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl peroxy-2-ethylhexanoate, dicumyl peroxide, lauryl peroxide; other redox-catalyzed compounds are used. can do. The amount of the polymerization initiator used is not particularly limited, and is about 0.1 to 5 parts by weight with respect to 100 parts by weight of all the monomer components constituting the component (A).

In addition, during polymerization, mercaptans such as 2-mercaptoethanol and n-dodecyl mercaptan; alcohols such as ethanol, isopropyl alcohol and pentanol; carbon tetrachloride, ethylbenzene, isopropylbenzene, cumene, α-methylstyrene dimer, 2, Chain transfer agents such as 4-diphenyl-4-methyl-1-pentene can also be used. The amount of the chain transfer agent used is not particularly limited, and is about 0.01 to 5 parts by weight with respect to 100 parts by weight of all the monomer components constituting the component (A).

As the conditions for the polymerization reaction, usually, the reaction temperature may be about 70 to 140 ° C. and the reaction time may be about 1 to 10 hours.

The pH of the polymer may be adjusted after the polymerization in order to make it more soluble in water. Various known pH adjusters can be used to adjust the pH, for example, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkaline soil such as calcium hydroxide. Metal hydroxides; amines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, triethylamine; ammonia and the like. The pH is not particularly limited, but is preferably adjusted to about 4 to 10.

From the viewpoint of emulsifying property, the obtained polymer preferably has a weight average molecular weight of about 1,000 to 100,000, more preferably about 5,000 to 50,000, and 20,000 to 40, About 000 is more preferable.

The starches are not particularly limited, and are, for example, unmodified starches such as corn starch, potato starch, tapioca starch, wheat starch, rice starch, and sago palm starch; cationized starch, oxidized starch, phosphoric acid-modified starch, and carboxymethylated starch. , Hydroxyethylated starch, carbamylethylated starch, cyanoethylated starch, dialdehyde-modified starch, processed starch such as acetic acid-modified starch and the like.

As for the physical characteristics of starches, from the viewpoint of emulsifying property, the weight average molecular weight is preferably about 10,000 to 500,000, more preferably about 150,000 to 450,000, and about 300,000 to 400,000. More preferred.

Further, as the starches, modified starch obtained by modifying the above-mentioned unmodified starch or modified starch (hereinafter, also referred to as “raw material starch”) with a treatment agent such as an inorganic peroxide, an enzyme or an inorganic acid can also be used.

The inorganic peroxide is not particularly limited, and is, for example, hypochlorite; ammonium persulfate (hereinafter, also referred to as APS), potassium persulfate (hereinafter, also referred to as KPS), sodium persulfate (hereinafter, also referred to as SPS). ) Etc., peroxodisulfate; hydrogen peroxide and the like. These may be used alone or in combination of two or more. Further, hydrogen peroxide may be combined with iron sulfate or copper sulfate.

The enzyme is not particularly limited, and examples thereof include α-amylase produced by various bacteria, animals and plants.

The inorganic acids are not particularly limited, and examples thereof include hydrochloric acid, sulfuric acid, phosphoric acid and the like. These may be used alone or in combination of two or more.

The amount of the treatment agent used is not particularly limited, but from the viewpoint of reactivity with the raw material starch, the solid content weight is preferably about 0.01 to 10 parts by weight with respect to 100 parts by weight of the raw material starch, and is 0. .1 to 6 parts by weight is more preferable.

The method for producing the modified starch is not particularly limited, and examples thereof include heating an aqueous solution containing starches and a treatment agent at a temperature of about 60 to 100 ° C. for about 30 to 60 minutes.

The physical characteristics of the modified starch obtained by the above-mentioned production method are not particularly limited, but for example, the Brookfield viscosity in an aqueous solution having a solid content concentration of 15% by weight is preferably about 5 to 1000 mPa · s at a temperature of 25 ° C., and 10 to 10 mPa · s. About 200 mPa · s is more preferable.

The weight average molecular weight of the modified starch is preferably about 10,000 to 500,000, more preferably about 15,000 to 100,000, and even more preferably about 20,000 to 50,000.

The amount of the component (A) used is usually about 20 to 200 parts by weight, preferably about 30 to 100 parts by weight, based on 100 parts by weight of the total of the components (B) and (C) in terms of solid content weight. is there. Within the above numerical range, the dispersion stability of the sizing agent and the size effect of the coated paper can be enhanced.

Further, as the component (A), in addition to the above-mentioned polymers or starches, a cationic surfactant, a nonionic surfactant, an anionic surfactant or the like may be used in combination.

The cationic surfactant is not particularly limited, and examples thereof include dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride and the like. As these commercially available products, for example, Katyogen H and Katyogen L manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Kotamine 24P, Kotamine 86P Cornk, Kotamine 60W, and Kotamine 86W manufactured by Kao Corporation can be obtained.

The nonionic surfactant is not particularly limited, and is, for example, polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene sorbitan fatty acid ester, and other nonionic surfactants in the molecule. Examples thereof include nonionic surfactants having a reactive functional group.

The anionic surfactant is not particularly limited, and for example, dialkyl sulfosuccinate, alkane sulfonate, α-olefin sulfonate, polyoxyethylene alkyl ether sulfosuccinate salt, polyoxyethylene styrylphenyl ether sulfosuccinic acid. Examples thereof include ester salts, naphthalin sulfonic acid formalin condensates, polyoxyethylene alkyl ether sulfates, and polyoxyethylene alkyl phenyl ether sulfates.

These other surfactants may be used alone or in combination of two or more.

The component (B) contains a polymer of a monomer component containing the component (b1) and is one component forming the core portion of the sizing agent, and contributes to the size effect of the coated paper.

The component (b1) is not particularly limited, and examples thereof include those exemplified by the above-mentioned component (a1). These may be used alone or in combination of two or more.

The amount of the component (b1) used is not particularly limited, but from the viewpoint of the size effect of the coated paper, the total of all the monomer components constituting the component (B) is 100% by weight, and usually about 10 to 80% by weight. It is preferably about 20 to 70% by weight.

The monomer component forming the component (B) is not particularly limited, and is, for example, a (meth) acrylic acid ester (b2) (hereinafter referred to as the (b2) component), an unsaturated monomer (b3) having a hydrophilic group (hereinafter referred to as the component). , (B3) component) and the like can be used together.

The component (b2) is not particularly limited, and for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. Examples thereof include isobutyl acid acid, -tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate. These may be used alone or in combination of two or more. Of these, isobutyl (meth) acrylate is preferable from the viewpoint of the size effect of the coated paper.

The amount of the component (b2) used is not particularly limited, but from the viewpoint of the size effect of the coated paper, the total of all the monomer components forming the component (B) is 100% by weight, and usually about 10 to 80% by weight. It is preferably about 20 to 70% by weight.

The component (b3) is not particularly limited as long as it does not correspond to the components (b1) and (b2), and is, for example, an unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid, and crotonic acid; itaconic acid, anhydrous. Unsaturated dicarboxylic acids such as itaconic acid, maleic acid, maleic anhydride, fumaric acid, muconic acid, citraconic acid; 2-hydroxymethyl (meth) acrylic acid, 2-hydroxyethyl (meth) acrylic acid, (meth) acrylic acid (Meta) acrylic acid hydroxyalkyl esters such as hydroxy n-propyl and (meth) acrylic acid hydroxyisopropyl; unsaturated monoalcohols such as allyl alcohol and metalyl alcohol; (meth) acrylic acid diethylene glycol, (meth) acrylic acid triethylene Examples thereof include polyalkylene glycol-based unsaturated monomers such as glycol, tetraethylene glycol (meth) acrylate, dipropylene glycol (meth) acrylate, tripropylene glycol (meth) acrylate, and tetrapropylene glycol (meth) acrylate. .. These may be used alone or in combination of two or more. Of these, acrylic acid is preferable.

The amount of the component (b3) used is not particularly limited, but from the viewpoint of the balance between the dispersion stability of the sizing agent and the size effect of the coated paper, the total of all the monomer components constituting the component (B) is set to 100% by weight. , Usually about 1 to 20% by weight, preferably about 5 to 20% by weight.

Further, as a monomer component (b4) (hereinafter referred to as (b4) component) other than the component (b2) and the component (b3), diethyl amide maleate, din-butyl maleate, isobutyl maleate, if necessary. , Unsaturated dicarboxylic acid dialkyl esters such as di-octyl maleate, di-decyl maleate, di n-dodecyl maleate, di-hexadecyl maleate; (meth) acrylate-N, N-diethylaminoethyl, Dialkylaminoalkyl esters of (meth) acrylates such as (meth) acrylate-N, N-diethylaminopropyl, (meth) acrylate-N, N-diethylaminobutyl; vinyl esters such as vinyl propionate, vinyl acetate; acrylonitrile, Ditrils such as metaacryllonitrile; N, N-dialkyl (meth) acrylamides such as N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide; N, N'-methylenebis (meth) acrylamide, N , N'-propylene bis (meth) acrylamide, bisacrylamide such as diacrylamide dimethyl ether; even if unsaturated monomers having a sulfonyl group such as vinyl sulfonic acid, sodium styrene sulfonate, sodium (meth) allyl sulfonate, etc. are used together. good. Further, it may be used alone or in combination of two or more. The amount of the component (b4) used is not particularly limited, but is preferably about 1 to 20% by weight, with the total of all the monomer components forming the component (B) being 100% by weight.

Further, if necessary, mercaptans such as 2-mercaptoethanol and n-dodecyl mercaptan; alcohols such as ethanol, isopropyl alcohol and pentanol; carbon tetrachloride, ethylbenzene, isopropylbenzene, cumene, α-methylstyrene dimer, 2, A chain transfer agent such as 4-diphenyl-4-methyl-1-pentene may be used. The amount of the chain transfer agent used is about 0.01 to 5 parts by weight with respect to 100 parts by weight of all the monomer components constituting the component (B).

The component (C) is an alkyl ketene dimer, and like the component (B), it is one component that forms the core of the sizing agent and contributes to the size effect of the coated paper. Further, due to the affinity with the component (A), the mechanical stability of the sizing agent is also improved, and the stain on the coating device or the like can be reduced.

The component (C) is represented by the following general formula (1) (R ¹ and R ² represent an alkyl group or an alkenyl group, respectively, and may be the same or different). There is no particular limitation.

The alkyl group is not particularly limited, and for example, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group and an eicosyl group. , Docosyl group, tetracosyl group, hexacosyl group, octacosyl group, triacontyl group, dotriacontyl group and the like. These may be branched.

The alkenyl group is not particularly limited, and for example, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tetradecenyl group, a hexadecenyl group, an octadecenyl group and an eicosenyl group. , Docosenyl group, tetracosenyl group, hexacosenyl group, octacosenyl group, triacontenyl group, dotoriacontenyl group and the like. These may be branched.

These components (C) may be used alone or in combination of two or more. Among them, from the viewpoint of size effect, it is preferable that R ¹ and R ² are represented by an alkyl group or an alkenyl group having 12 to 24 carbon atoms, respectively, in the general formula (1), and R ¹ and R ² are respectively. Those represented by alkyl groups having 14 to 24 carbon atoms, that is, tetradecyl group (carbon number: 14), hexadecyl group (carbon number: 16), octadecyl group (carbon number: 18), ecosil group (carbon number: 20). ), Dococil group (carbon number: 22), tetracosyl group (carbon number: 24) are more preferable.

The ratio of the component (B) and the component (C) used [(B) / (C)] is usually about 30/70 to 99/1 in terms of solid content weight from the viewpoint of mechanical stability of the sizing agent. It is preferably about 50/50 to 95/5, more preferably about 60/40 to 90/10.

The surface sizing agent for papermaking of the present invention can be obtained by various known production methods. The production method is not particularly limited, and for example, the monomer component and the component (C) forming the component (B) are charged into the component (A), and solution polymerization, emulsion polymerization, and suspension polymerization are carried out in the presence of a polymerization initiator. In the present invention, the monomer component forming the component (B) and the monomer component forming the component (B) and the component (C) are included in the component (A) from the viewpoint of the polymerizable property of the monomer component forming the component (B) and the component (C). ) Is dropped and emulsion-polymerized, more specifically, in the presence of the component (A) and the polymerization initiator, the component (B) and (C) are dropped and emulsion-polymerized. In particular, it is preferable to add a mixed solution of the monomer component forming the component (B) and the component (C) because the mechanical stability and sizing effect of the obtained sizing agent are excellent. The conditions for emulsion polymerization are not particularly limited, but the temperature is usually about 40 to 150 ° C. (preferably about 60 to 100 ° C.), and the time is usually about 1 to 10 hours (preferably about 1 to 3 hours). is there.

The polymerization initiator is not particularly limited, and for example, peroxides such as hydrogen peroxide, ammonium persulfate, and potassium persulfate; tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, and dich. Organic peroxides such as mill peroxide and lauryl peroxide; azo compounds such as 2,2'-azobisisobutyronitrile and dimethyl-2,2'-azobisisobutyrate, etc. are mentioned, and these are examples. It may be used alone or in combination of two or more. The amount of the polymerization initiator used is also not particularly limited, and is usually about 0.1 to 10 parts by weight, preferably about 1 to 5 parts by weight, based on 100 parts by weight of all the monomer components constituting the component (B). Is.

A sulfite such as sodium sulfite, a hydrogen sulfite such as sodium hydrogen sulfite, triethanolamine, cuprous sulfate and the like may be used in combination with the polymerization initiator.

Further, in the production of the surface sizing agent for papermaking, a solvent may be used if necessary.

The solvent is not particularly limited, and for example, alcohols such as ethyl alcohol and isopropyl alcohol; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as toluene and benzene; organic solvents such as ethyl acetate, chloroform and dimethylformamide, and organic solvents such as ethyl acetate, chloroform and dimethylformamide. Examples thereof include water and a mixed solvent of the organic solvent and water.

The physical properties of the surface sizing agent for paper making of the present invention are not particularly limited, and for example, the volume average particle diameter of the emulsion particles by the light scattering method is usually about 50 to 300 nm, preferably about 50 to 150 nm, more preferably. It is about 50 to 80 nm. By setting such a numerical range, the mechanical stability of the sizing agent and the size effect of the coated paper can be balanced.

The Brookfield viscosity at a solid content concentration of 25% by weight and a temperature of 25 ° C. is usually about 10 to 200 mPa · s, preferably about 30 to 80 mPa · s.

The pH at a temperature of 25 ° C. is usually about 7 to 11, preferably about 7.5 to 9.5. When adjusting the pH, various known pH adjusting agents can be used. The pH adjuster is not particularly limited, and for example, inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; and alkaline earth metal hydroxides such as calcium hydroxide. Ammonia such as monomethylamine, dimethylamine, monoethylamine, diethylamine, triethylamine; ammonia and the like.

If necessary, the surface sizing agent for papermaking of the present invention may be added with additives such as an antioxidant, an antifoaming agent, a preservative, a chelating agent, and a water-soluble aluminum compound.

As the coating liquid containing the surface sizing agent for papermaking of the present invention, the sizing agent may be used as it is or diluted with water or the like, but various known additives may be blended as needed. Examples of the additive include oxidized starch, phosphoric acid esterified starch, self-modified starch, cationized starch, starches such as amphoteric starch, celluloses such as carboxymethyl cellulose, polyvinyl alcohols, polyacrylamides, sodium alginate and the like. Paper strength enhancers such as water-soluble polymers, antislip agents, preservatives, rust preventives, pH adjusters, antifoaming agents, thickeners, fillers, antioxidants, water resistant agents, film-forming aids , Pigments, dyes and the like.

The solid content concentration of the coating liquid is not particularly limited, but is usually used in the range of about 0.5 to 30% by weight, preferably 1 to 20% by weight.

The present invention also relates to coated paper. The coated paper contains a surface sizing agent for papermaking, and specifically, the coating liquid is applied to the surface of the base paper.

The base paper is not particularly limited, and usually uncoated paper and paperboard made from wood cellulose fibers can be used. The base paper is obtained from papermaking pulp, and examples of the papermaking pulp include chemical pulps such as broadleaf pulp (LBKP) and coniferous pulp (NBKP); crushed wood pulp (GP) and refiner ground pulp. (RGP), mechanical pulp such as thermomechanical pulp (TMP); used paper pulp such as used cardboard paper and the like. In addition, various chemicals such as a filler, an internal sizing agent, and a paper strength enhancer may be added to the base paper.

Further, the coating means of the coating liquid is not particularly limited, and various known methods such as an impregnation method, a size press method, a gate roll method, a bar coater method, a calendar method, and a spray method can be applied. The coating amount of the coating liquid (concentration) is not particularly limited, usually, 0.005~1g / ^{m 2} approximately, and preferably from 0.01 to 0.5 g / ^{m 2} approximately.

The coating paper obtained by the above means is not particularly limited, and for example, recording paper such as foam paper, PPC paper, and heat-sensitive recording paper: art paper, cast coated paper, coated paper such as high-quality coated paper; kraft paper, Wrapping paper such as pure white roll paper; various types of paper (Western paper) such as notebook paper, book paper, printing paper, newspaper paper; paperboard for paper containers such as Manila balls, white balls, and chip balls; paperboards such as liners and cores. Be done.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, parts and% in Examples and Comparative Examples are based on weight.

(Weight average molecular weight)
The molecular weight was measured by the gel permeation chromatography (GPC) method under the following measurement conditions.
GPC body: Tosoh Co., Ltd. column: Tosoh Co., Ltd. guard column TSK gel guard column α 1 and TSK-GEL α-M 2 (temperature 40 ° C)
Eluent: 0.2 mol / L sodium nitrate buffer (sodium nitrate (manufactured by Wako Pure Chemical Industries, Ltd.)
Flow velocity: 1.0 mL / min Detector:
Viscotec TDA MODEL301 (concentration detector and 90 ° light scattering detector and viscosity detector (temperature 40 ° C)) RALLS method Standard substance: Polyethylene oxide measurement sample: (A) component is 0.5% in solid content concentration The eluent is added to adjust the measurement sample, an aqueous sodium hydroxide solution is added until the pH reaches 10 to 12, soaked in a hot water bath at 80 ° C. or higher for 1 hour, and then adjusted to pH 6 to 8 with sulfuric acid. Then, it was diluted to 0.025% with an eluent and measured.

(viscosity)
The viscosity of the sample adjusted to 25 ° C. was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

(PH)
The pH of a sample (solid content concentration 25%) adjusted to 25 ° C. was measured using a commercially available measuring machine (product name "pH METER F-14", manufactured by HORIBA, Ltd.).

(Volume average particle size)
The measurement was performed using a light scattering particle size analyzer (product name "ELSZ-2", manufactured by Otsuka Electronics Co., Ltd.).

Production Example 1 (Production of Polymer (A-1))
85 parts of isopropyl alcohol, 43 parts of ion-exchanged water, 125.9 parts of styrene (70% of all monomer components), 67.5 parts of 80% acrylic acid in a flask equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer. While stirring the mixed solution (30% of all monomer components) under a nitrogen stream, the temperature was raised to 70 ° C., and tert-butylperoxy-2-ethylhexanoate (trade name "Perbutyl O" Nippon Oil & Fats Co., Ltd.) ) Was prepared in 7.3 copies. The temperature was further raised to 80 to 90 ° C. and kept warm for 4 hours to obtain a polymer, and then 200 parts of ion-exchanged water, 0.045 parts of hydroquinone and 51.0 parts of a 48% potassium hydroxide aqueous solution (in the polymer). (Equivalent to 50 mol% with respect to the anionic group of) was charged and neutralized, and then isopropyl alcohol was distilled off. Further, 29.7 parts of 25% aqueous ammonia (corresponding to 50 mol% with respect to the anionic group in the copolymer) was added and dissolved to obtain a polymer (A-1) having a solid content concentration of 25%. The weight average molecular weight of the component (A-1) is shown in Table 1 (the same applies hereinafter).

Production Example 2 (Production of Polymer (A-2))
70.3 parts of diisobutylene (2,4,5-trimethyl-1-pentene; purity 76%) in a reaction vessel equipped with a stirrer, a condenser tube, two dropping funnels, a nitrogen introduction tube and a thermometer (all monomers). 53.4% of the components), 46.6 parts of maleic anhydride (46.6% of the total monomer components), and 180 parts of toluene were stirred under a nitrogen stream and heated to 70 ° C. and tert. 7.3 parts of -butylperoxy-2-ethylhexanoate (trade name "Perbutyl O", manufactured by Nippon Oil & Fats Co., Ltd.) was charged. The temperature was further raised to 80 to 90 ° C. and kept warm for 4 hours to obtain a polymer, and then 200 parts of ion-exchanged water, 0.045 parts of hydroquinone and 35.0 parts of a 48% potassium hydroxide aqueous solution (in the polymer). (Equivalent to 100 mol% with respect to the anionic group) was charged and neutralized, and then toluene was distilled off to obtain a polymer (A-2) having a solid content concentration of 20%.

Production Example 3 (Production of Polymer (A-3))
70 parts of styrene, 30 parts of methacrylic acid-N, N-dimethylaminoethyl, 42.9 parts of isopropyl alcohol, and 2, in a flask equipped with a stirrer, a cooling tube, a dropping rotor, a nitrogen introduction tube and a thermometer. 2.5 parts of 2'-azobisisobutyronitrile was charged, and the polymerization reaction was carried out at 80 to 85 ° C. for 5 hours while stirring under a nitrogen stream. Then, after adding 11.5 parts of acetic acid and 300 parts of water, 17.7 parts of epichlorohydrin was added and kept warm at 80 ° C. for 2 hours, and a predetermined amount of water was further added to adjust the solid content concentration to 20%. The polymer (A-3) was obtained.

Production Example 4 (Production of APS-modified starch (A-7))
In a flask equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen introduction tube, 100 parts of corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd., solid content concentration 88%), 5 parts of APS , And 300 parts of water were added, the temperature was raised to 90 ° C., and the mixture was stirred for 1 hour. Then, water was added so that the solid content concentration became 15%, and then the mixture was cooled to 40 ° C. to obtain APS-modified starch (A-7).

Production Example 5 (Production of enzyme-modified starch (A-8))
In a flask equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen introduction tube, 100 parts of corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd., solid content concentration 88%), Crystar- 0.1 part of Ze L1 (manufactured by Amano Enzyme Co., Ltd.) and 300 parts of water were added, the temperature was raised to 75 ° C., the temperature was raised to 90 ° C., and the mixture was further stirred for 10 minutes. Then, water was added so that the solid content concentration became 15%, and then the mixture was cooled to 40 ° C. to obtain an enzyme-modified starch (A-8).

Production Example 6 (Production of sulfuric acid-modified starch (A-9))
In a flask equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen introduction tube, 250.0 parts of corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd., solid content concentration 88%), 11 parts of a 20% aqueous sulfuric acid solution (2.2 parts of solid content) and 300 parts of water were added, the temperature was raised to 90 ° C., and the mixture was stirred for 1 hour. Then, water was added so that the solid content concentration became 15%, and then the mixture was cooled to 40 ° C. to obtain sulfuric acid-modified starch (A-9).

Example 1
50 parts (solid content) of polymer (A-1), 200 parts of ion-exchanged water, anionic surfactant in a reaction vessel equipped with a stirrer, cooling pipe, nitrogen introduction pipe, thermometer and two dropping rotors. 2 parts of activator (trade name: "Hitenol LA10", weight average molecular weight: 300, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 0.08 part by weight of iron (II) sulfate heptahydrate, and a reaction vessel After sufficiently replacing the oxygen in the system with nitrogen, the temperature inside the system was raised to 80 ° C. with stirring. Next, a mixture of alkyl keten dimer (chloride palmitate / chloride stearate = 5/95 (solid content weight)) was condensed with a monomer mixture of 56 parts of styrene and 24 parts of n-butyl acrylate in the dropping rotor (I). 20 parts of the solution was added to the dropping rotor (II), and 10 parts of hydrogen peroxide solution having a solid content concentration of 35% (3.5 parts by weight with respect to the monomer component) was added to 100 parts of water. Each of the dissolved aqueous solutions was charged, dropped into the system over about 2 hours, and kept warm for another 2 hours to complete the reaction to obtain a surface sizing agent for papermaking having a solid content concentration of 20.5%. Table 1 shows the viscosity, pH, and volume average particle size of the obtained surface sizing agent for papermaking (the same applies hereinafter).

Examples 2 to 20, Comparative Examples 1 to 4
The components and amounts used in Table 1 were changed and synthesized in the same manner as in Example 1 to obtain surface sizing agents for papermaking. In Comparative Example 3, the component (A) was not used as the surfactant, and only two parts of the anionic surfactant (High Tenor LA10) was used.

(Mechanical stability)
50 g of a surface sizing agent for papermaking was weighed in a container of a Marlon type stability tester (manufactured by Shinsei Sangyo Co., Ltd.), and was generated after vigorous stirring at a temperature of 25 ° C., a load of 10 kg, and a rotation speed of 1000 rpm for 5 minutes. The agglomerates were filtered through a pre-weighed 350 mesh wire mesh. After drying in a circulation dryer at 105 ° C. for 3 hours, the weights of the wire mesh and the agglomerates were measured, and the solid content weight of the agglomerates was determined. The value was calculated according to Equation 1 and judged according to the following evaluation criteria.

(Equation 1) Mechanical stability (%) = (solid content weight (g) of agglomerates / solid content weight (g) of surface sizing agent for papermaking) × 100

(Evaluation criteria)
⊚: The calculated value is less than 0.5% ○: The calculated value is 0.5% or more and less than 1.0% Δ: The calculated value is 1.0% or more and less than 5.0% ×: The calculated value is 5 .0% or more

(Preparation of coating liquid)
Corn starch (trade name: "Oji Ace A", manufactured by Oji Corn Starch Co., Ltd.) was diluted with deionized water so that the solid content concentration was 12%, and APS was added to the solid content weight of the starch. 6% was added and the mixture was kept warm at 90 ° C. for 20 minutes. The mixture was diluted with deionized water so that the solid content concentration was 7.5%, and adjusted to pH 5.0 with a 48% aqueous sodium hydroxide solution to obtain APS-modified starch. 1.47 parts of the surface sizing agent for papermaking of Example 1 was mixed with 50 parts of the APS-modified starch to prepare a coating liquid. The solid content concentration of the paper-making surface sizing agent in the coating liquid is 0.88%. Further, the same applies to the surface sizing agents for papermaking of Examples 2 to 20 and Comparative Examples 1 to 4, and a coating liquid was prepared.

(Effervescence of coating liquid)
Each coating liquid was heated to 50 ° C., treated with a household mixer for 2 minutes, and then the height of the liquid level immediately after the treatment was measured (the initial liquid level was 40 mm).

(Preparation of coated paper and evaluation of size effect)
Using a bar coater, each coating liquid whose liquid temperature was adjusted to 50 ° C. was double-sided coated on the surface of high-quality acid-free paper (Sutekihito size: 0.5 seconds, basis weight: 70 g / m ² ). After that, it was dried with a rotary dryer at 105 ° C. for 1 minute to prepare a coated paper. The amount of the surface sizing agent for papermaking attached to the base paper was about 0.08 g / m ² in terms of solid content, and the amount of starch attached was about 2 g / m ² in terms of solid content. The degree of nice human size of the obtained coated paper was measured according to JIS P 8122. The larger the value, the better the size effect.

<Ingredient (A)>
-A-1: Polymer of Production Example 1-A-2: Polymer of Production Example 2-A-3: Polymer of Production Example 3-A-4: Corn starch (trade name: "Oji Ace A" , Made by Oji Cornstarch Co., Ltd.)
・ A-5: Tapioca starch ・ A-6: Potato ・ A-7: APS-modified starch of Production Example 4 ・ A-8: Enzyme-modified starch of Production Example 5 ・ A-9: Sulfate-modified starch of Production Example 6 < (B) Ingredient>
B-1: St / BA = 70/30 (weight ratio (solid content conversion))
B-2: St / IBMA = 70/30 (weight ratio (solid content conversion))
B-3: St / BA / AA = 65/20/15 (weight ratio (solid content conversion))
B-4: St / BA / DM = 65/20/15 (weight ratio (solid content conversion))
* St-styrene, n-butyl BA-acrylate, isobutyl IBMA-methacrylate, AA-acrylic acid, DM-methacrylic acid-N, N-dimethylaminoethyl <(C) component>
-C-1: Condensation of a mixture of palmitic acid chloride / stearic acid chloride = 5/95 (solid content weight) -C-2: Palmitic acid chloride / stearic acid chloride = 35/65 (solid content weight) Condensation of mixture ・ C-3: Condensation of mixture of chloride chloride / chloride stearate = 90/10 (solid content weight)

Claims (10)

A shell portion containing a surfactant (A) having a weight average molecular weight of 1,000 to 500,000, and a core portion containing a polymer (B) of a monomer component containing styrenes (b1) and an alkyl ketene dimer (C). Surface sizing agent for papermaking containing emulsion particles having. The surface sizing agent for papermaking according to claim 1, wherein the amount of the component (A) used is 20 to 200 parts by weight with respect to 100 parts by weight of the total of the components (B) and (C) in terms of solid content weight. .. The first or second claim, wherein the component (A) contains a polymer of a monomer component containing at least one selected from the group consisting of styrenes (a1) and α-olefins (a2), and / or starches. Surface sizing agent for papermaking. The surface sizing agent for papermaking according to any one of claims 1 to 3, wherein the monomer component forming the component (B) further contains a (meth) acrylic acid ester (b2). The surface sizing agent for papermaking according to any one of claims 1 to 4, wherein the monomer component forming the component (B) further contains an unsaturated monomer (b3) having a hydrophilic group. The surface sizing agent for papermaking according to any one of claims 1 to 5, wherein the component (C) is represented by the general formula (1).
(In the formula, R ¹ and R ² represent an alkyl group or an alkenyl group having 12 to 24 carbon atoms, respectively, and may be the same or different.) Any of claims 1 to 6, wherein the ratio of the component (B) and the component (C) used is (B) / (C) = 30/70 to 99/1 in terms of solid content weight. Surface sizing agent for papermaking described in. The surface sizing agent for papermaking according to any one of claims 1 to 7, wherein the volume average particle diameter of the emulsion particles is 50 to 300 nm. The production of the surface sizing agent for papermaking according to any one of claims 1 to 8, wherein the monomer component forming the component (B) and the component (C) are added dropwise to the component (A) to carry out emulsion polymerization. Method. A coated paper containing the surface sizing agent for papermaking according to any one of claims 1 to 8.